S.C. Code Ann. § 12-8-1070: Manner of withholding and amount deducted and withheld determined according to rules or regulations of department.

If payment of wages is made to an employee by an employer:

(1) with respect to a payroll period or other period, a part of which is included in a payroll period or other period with respect to which wages are also paid to the employee by the employer;

(2) without regard to a payroll period or other period but on or before the expiration of a payroll period or other period with respect to which wages are also paid to an employee by an employer;

(3) with respect to a period beginning in one and ending in another calendar year; or

(4) through an agent, fiduciary, or other person who also has the control, recent custody, disposal of or pays the wages payable by another employer to the employee; the manner of withholding and the amount to be deducted and withheld under this article must be determined in accordance with rules or regulations promulgated by the department under which the withholding exemption allowed to the employee in a calendar year approximates the withholding exemption allowable with respect to an annual payroll period.